(1) Field of the Invention
The invention is related to a bearing arrangement with at least one first bearing layer and at least one second bearing layer, said bearing arrangement comprising the features of claim 1.
(2) Description of Related Art
Generally, bearing arrangements with at least one first bearing layer and at least one second bearing layer can be classified broadly with respect to their allowed motions. Accordingly, four broad bearing arrangement categories can be defined, i.e. hinge motion bearing arrangements that are configured to allow hinge motion, spherical bearing arrangements that are configured to allow spherical rotation, radial bearing arrangements that are configured to allow axial rotation and translational bearing arrangements that are configured to allow linear motion.
Hinge motion bearing arrangements are well-known by the skilled person and, for instance, used in doors, windows and the like. However, such hinge motion bearing arrangements are irrelevant to the present application, so that a detailed description thereof can be omitted for brevity and conciseness.
Spherical bearing arrangements are also well-known by the skilled person and, for instance, described in the documents CN 202 833 642 U, US 2011/0206303 A1, WO 2011/008704 A1, IT RM2009/0222 A1, WO 2010/037476 A2, WO 2009/108644 A1, US 2009/0212558 A1, JP 2007/069820 A, EP 1 605 173 A1, CN 2 677 102 U, US 2004/0184869 A1, EP 1 199 483 A1, U.S. Pat. No. 5,601,408 A, DE 41 38 609 A1, HU 9 104 038 D0, FR 2 642 121 A1, DE 31 32 711 01, U.S. Pat. No. 8,102,321 A, U.S. Pat. No. 4,121,861 A and DE 25 20 947 A1. Therefore, a more detailed description of such spherical bearing arrangements is omitted hereinafter for brevity and conciseness.
Radial bearing arrangements are also well-known by the skilled person and, for instance, described in the documents CN 102 852 975 A, DE 10 2011 077816 A1, DE 10 2011 077814 A1, CN 202 468 702 U, EP 2 503 164 A1, DE 10 2011 001902 A1, RU 2010/127030 A, DE 10 2010 012474 A1, WO 2011/062257 A1, DE 10 2009 022206 B3, CN 201 606 408 U, DE 10 2008 049813 A1, CN 201 412 443 U, DE 10 2007 062290 A1, CA 2 636 221 A1, CN 200 989 377 U, FR 2 910 090 A1, DE 10 2006 051643 A1, WO 2008/047046 A1, DE 10 2006 004297 A1, RU 2005/119120 A, DE 10 2005 027503 A1, WO 2006/045389 A1, DE 10 2004 014775 A1, DE 20 316 009 U1, IT MI2004/0569 A1, CN 2 573 752 U, WO 2004/002762 A1, SE 2002/00617 D0, RU 2 224 146 02, DE 100 39 573 01, JP 2000/027857 A, DE 41 12 253 A1, FR 2 663 090 A1, JP H028512 A, U.S. Pat. No. 4,664,539 A, IT 8 220 932 D0, DE 26 39 893 A1, DE 27 26 914 A1, U.S. Pat. No. 3,950,964 A, IT 964 486 B, DE 21 55 048 A1, U.S. Pat. No. 2,958,563 A, DE 870 047 0, DE 729 032 C and DD 49729 A. Therefore, a more detailed description of such bearing arrangements is also omitted hereinafter for brevity and conciseness.
An exemplary translational bearing arrangement is described in the document CN 101 908 668 U. This translational bearing arrangement is embodied in the form of a multi-layer bearing with plural bearing layers and comprises an outer bearing ring, an inner bearing ring, multi-layer sliding modules which are evenly arranged in an annular space between the outer bearing ring and the inner bearing ring, as well as constraint mechanisms which are arranged at both ends or suitable intermediate positions of the multi-layer sliding modules. The constraint mechanisms are used for constraining the multi-layer sliding modules and are arranged in the constraint mechanisms. More specifically, the constraint mechanisms are implemented by reset springs or diaphragms that are used at each end of the multi-layer bearing in order to retain associated sliding rails that define the multi-layer sliding modules. Using this arrangement, the sliding rail of the inner bearing ring can be moved with a higher distance than the sliding rail of the outer bearing ring, as the moment caused by the reset spring or diaphragm decreases towards the inner bearing ring.
In all of the above-described bearing arrangements, associated bearing layers are provided that are configured to enable a relative movement between corresponding bearing support elements by means of associated bearing means. Such movements are characterized by the relative speed between the associated bearing layers or bearing layer components, which determines, at least to some extent, the durability of the underlying bearing arrangements. Furthermore, there are application-specific maximum values for the relative velocities between the bearing means and the bearing support elements, which limit e.g. the selection of applicable bearing means and their dimensions in comparatively high loaded bearing arrangements.
More specifically, in a bearing arrangement with a single bearing layer or plural bearing layers that are arranged in parallel, corresponding bearing support elements that are usually implemented as bearing rings are movable relative to each other by associated bearing means. However, the relative speed which is realizable with such bearing layers depends, for a given angular rotation rate and amplitude, on the diameter of the bearing rings, so that a maximum rotational speed of the bearing arrangement is limited by a maximum diameter of its bearing rings. This limits a frequently desired high shaft diameter in lightweight designs.
Especially, with so-called low-maintenance and maintenance-free bearing arrangements, an underlying durability is proportional to the product of surface pressure and relative velocity (P×V) between the bearing rings. Therefore, service life duration can only be modified by varying an underlying width of such bearing arrangements, as the value of this product (P×V) is independent from a respectively given diameter of the bearing rings. However, the width of the bearing arrangement cannot be sized arbitrarily. Therefore, at comparatively high loads, high angular frequencies and amplitudes, the application of low-maintenance or maintenance-free bearing arrangements is not possible.
Furthermore, concentrically arranged bearing arrangements are usually not used to provide redundancy, since associated resistors, e.g. friction, of the bearing arrangements usually always vary in their respective realization and are, thus, hardly dependent on the realizable relative speed. Accordingly, associated bearing support elements with the lowest resistances move with the highest relative speed and all other bearing support elements move with a much lower relative speed, or remain static. Such relative velocities are, however, not defined.
Moreover, elastomeric bearing arrangements usually comprise concentrically arranged elastomeric layers which are separated by rigid intermediate layers, e.g. steel. These intermediate layers support the elastomeric layers, which would otherwise be squeezed out laterally because of an underlying, relatively high transverse contraction occurring at comparatively high loads, and the bearing arrangement would, thus, fail. The number of elastomeric layers is based on a given load and total thickness of the elastomeric layers, and not on the rotational angle frequency.
However, elastomeric bearings generally have a limited storage time, a relatively high mass and high dispersion of quality and durability. Furthermore, the maximum rotation angle depends on the total thickness of the elastomeric layers and a given yield point of a respectively applied elastomer. Since the applied elastomer is simultaneously subjected to compressive stresses and shear stresses, it cannot be optimized for only one given type of load, but it needs at least to represent an acceptable compromise for both types of loads.